Background
Circadian misalignment is associated with metabolic syndrome. This study aimed to examine the association between circadian rhythm-disturbing factors and metabolic syndrome.
Methods
We used data from the 7th and 8th Korea National Health and Nutrition Examination Survey conducted between 2016 and 2020, which surveyed 16,253 individuals. Circadian rhythm-disturbing factors were defined as follows: sleep duration outside the reference group (6–8 hours), irregular breakfast, shift work, and physical inactivity. The adjusted odds ratio (aOR) for metabolic syndrome was calculated based on the number of circadian rhythm-disturbing factors present in adults over the age of 19 years.
Results
Among a total of 16,253 participants (mean age 48.2±15 years), metabolic syndrome was found in 5,237 participants (29.3%). The participants were classified into three categories based on the number of circadian rhythm-disturbing factors as follows: 2,627 (15.6%) did not have any factors, 6,406 (38.13%) had one factor, and 7,220 (46.3%) had two or more factors. Participants with a single circadian rhythm-disturbing factor were 21% more likely to have metabolic syndrome (aOR, 1.21; 95% confidence interval [CI], 1.08–1.36), and participants with two or more factors were 27% more likely to have metabolic syndrome (aOR, 1.27; 95% CI, 1.12–1.43).
Conclusion
Circadian rhythm-disturbing factors were significantly associated with the prevalence of metabolic syndrome in Korean adults. This finding has potential clinical implications for maintaining circadian rhythms by avoiding certain factors to prevent metabolic syndrome. Further studies are required to confirm these findings.

Citations

• Cumulative circadian disruption factors and metabolic syndrome
  Jungun Lee
  Korean Journal of Family Medicine.2025; 46(3): 125.     CrossRef

Background
There are incoherent studies about the effect of night shift work on circadian diurnal rhythms of cardiovascular parameters. Our study aimed to assess the alteration of circadian diurnal rhythms of cardiovascular parameters by night shift work. Methods: We studied 26 healthy nurse volunteers engaged in 3 shift work. From March 16 to April 30, 2006, ABPM (ambulatory blood pressure monitoring) was performed to each nurse two times during the day and night shift. Three nurses were excluded due to pain omdiced by ABPM. Blood pressure and heart rate was monitored every 30 minutes. Paired T-test was used for statistical analysis. Results: The mean arterial pressure, the mean systolic pressure, the mean heart rate and the mean pulse pressure during the overall period were significantly higher in the night shift than the day shift (P-value: ＜0.05, ＜0.001, ＜0.05, and ＜0.001, respectively). The mean arterial pressure, the mean diastolic pressure and the mean heart rate during in-hospital working period were significantly higher in the day shift (P-value: ＜0.05, ＜0.001, and ＜0.05, respectively). All parameters during the daytime sleep period after the night shift were significantly higher than during the nighttime sleep period after the day shift (P-values: ＜0.001). Proportional percentile falls of 3 parameters (systolic pressure, diastolic pressure, and heart rate) during the daytime sleep period after the night shift were significantly less than during the nighttime sleep period after the day shift (P-values: ＜0.001). Conclusion: The night shift work caused significant alteration in homeostasis of autonomic nervous system associated with circadian diurnal rhythms of cardiovascular parameters. (J Korean Acad Fam Med 2007;28: 187-194)

Background
: There are a few studies on the effects of job-strain on the prevalence of sleep problems in the foreign countries. In Korea, it has not been studied till now. In this article, the combined effects of job strain, shift work and some life-style on the prevalence of sleep proplems were studied among workers in middle-aged men.

Methods : 998 cases were chosen from 1109 men who visited health screening certer form October to November, 1999. Sleep problems were categorized to insomnia, sleep deprivation, daytime sleepiness and snoring on the base of result of factor analysis of 11 questions. Job strain was measured by 11 questions which developed by Karasek by and Theorell. All data set were analyzed using Chi-square test and multiple logistic regression analysis.

Results : The 4 sleep problems were analyzed by multiple logistic regression analysis in relation to job strain, shift work, occupation, obesity, sedentary life-style, smoking, drinking. Insomnia was increased significantly from highest job-strain group (Odds ratio (OR:2.02)) and non-exercise group(OR:2.05). In these groups, daytime sleepiness was increased significantly(OR=1.92 in the highest job-strain group, OR=1.72 in non-exercise group). Sleep deprivation was increased in the highest job-strain group(OR=2.18), managers & clerks(OR:1.67) and non-exercise group(OR:1.78). Snoring was increased from BMI(Body mass index) ≥25(OR=1.77), BMI ≥27(OR=2.80) and non-exercise group(OR:1.87).

Conclusion : In the highest job strain group, insomnia, sleep deprivation and daytime sleepiness was increased significantly. And sedentary life-style increased all sleep problems.